[CART360] Magnetic Sensor

[Vincent Leclerc]

This is the hall effect sensor I showed in class:
http://www.allegromicro.com/en/Products/Part_Numbers/3213/3213.pdf

They are omnipolar, which means they can be triggered by either a north or
south magnetic field.
Digikey sells them for $1.76.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=620-1043-ND

For HB LEDs, go to http://ledz.com/?p=led.power
They have 3W (3.5V, 700mA) LEDs that will blind you. They might have a
minimum order qtt so you may want to try eBay for the same type of product.
http://business.shop.ebay.ca/Business-Industrial-/12576/i.html?_nkw=3w+led&_catref=1&_fln=1&_sac=1&_trksid=p3286.c0.m282

DON'T FORGET to heatsink these LEDs. They emit a lot of heat and it needs to
be properly dissipated with an aluminum heatsink. If you don't, they will
last only several hours.

You drive them with a mosfet and use a current limiting resistor like a
normal LED with the formula V=RI.

In that case at 5V:

5 - 3.5 = R * 0.7
1.5 = R * 0.7
R = 2.1 Ohms

You will need a special power resistor, because so much current will go
through it. With the formula P = VI we get:

P = 1.5 * 0.7
P = 1.05 Watt

So to be safe, you need a 3 Ohm, 2 Watt resistor like so:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=3.0W-2-ND


Vincent



On Mon, Oct 19, 2009 at 5:20 PM, Alec Mathewson <alec.mathewson at gmail.com>wrote:

> Hey Vincent
>
> I want to buy a couple Magnetic sensors and strong LED's I can strobe.
> Anything particular I need to consider regarding the ones you had posted?
>
> Alec
>
>


-- 
Vincent Leclerc

Creative | Technical Director, ESKI Inc.
1751 Richardson, Suite 4311
Montreal, QC, Canada, H3K 1G6
http://eskistudio.com/
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Part-time Faculty, Design and Computation Arts
Concordia University, Montreal, QC, Canada
http://hybrid.concordia.ca/~cart360_vincent/

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